1. Field of the Invention
The present invention relates to a collision type fuel injection nozzle and a method of manufacturing the nozzle, particularly to a collision type fuel injection nozzle that can be manufactured with good precision, and to a method of manufacturing the nozzle.
2. Description of the Prior Art
A drawback with conventional collision type fuel injection nozzles has been the difficulty of machining the nozzle section, which has elevated production costs. A fuel injection nozzle disclosed by JP-A-HEI-4-125666 will be described with reference to FIG. 2. FIG. 2 shows a cross-section of the fuel injection nozzle 1, which has a nozzle body 2, a needle valve 3 and a sleeve 4. Formed in the nozzle body 2 is a fuel reservoir 6, a nozzle sac 7, at least one pair of first injection nozzle holes 8 and one pair of second injection nozzle holes 9, and a collision recess 10 at the tip. The pair of first injection nozzle holes 8 and pair of second injection nozzle holes 9 are joined by connecting portions exposed to the outside which are covered by a sleeve 4.
The needle valve 3 is seated on a seat 11 under a prescribed pressure of a nozzle spring (not shown). A rise in the fuel pressure lifts the needle valve 3 from the seat 11 and allows fuel to be injected at a prescribed pressure into the collision recess 10, via the pair of first injection nozzle holes 8 and pair of second injection nozzle holes 9. The second injection nozzle holes 9 are disposed in mutual opposition in the collision recess 10, so that jets of fuel come from each side of the collision recess 10 and collide with each other, producing a mist which is supplied to a combustion chamber 12.
In order to ensure that the jets of fuel collide with good precision, when the fuel injection nozzle is being manufactured the second injection nozzle holes 9 have to be precisely formed so that the central axes (centers) of the opposed second injection nozzle holes 9 are in alignment. However, in the case of the conventional fuel injection nozzle 1, each of the pair of second injection nozzle holes 9 has to be formed separately, which can give rise to a misalignment of the centers of the second injection nozzle holes 9 that makes it difficult to ensure full collision of the jets of fuel in the collision recess 10, without which it is difficult to obtain a uniformly atomized fuel spray.